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Vintage MotorHome #117933 07/19/04 07:08 PM
Joined: Oct 2000
Posts: 3,632
Admin Offline OP
Here are some pictures of a '70s vintage motorhome I was troubleshooting this afternoon.

Complaint was: the coach was plugged in, the customer kneeled down wearing a pair of shorts, and received a shock when he went to lift the outside access door to the generator.

Cover removed from the FPE box:
[Linked Image]
EGC connection to frame
[Linked Image]
EGC routing
[Linked Image]
Working space
[Linked Image]
Location - its under the wooden cover
[Linked Image]
The plug looks fine but the ground pin is no longer connected to the conductor
[Linked Image]
Everything was actually wired correctly to the breaker box. The problem is a hot to ground short in one of the 120 receptacle circuits. Everything worked and nothing seemed to be wrong except for the shock. Because the ground circuit was not actually connected and the motorhome was sitting on rubber tires, the short to ground had no operational effect. The customer never got a shock climbing in or out because he always wears rubber soled shoes. Only when his bare knee was on the ground did he get bit. I have not located the short yet but as soon as the ground was repaired, it immediately tripped a breaker.

- Big Jim

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Re: Vintage MotorHome #117934 07/19/04 09:00 PM
Joined: Sep 2001
Posts: 806
NJwirenut Offline
An FPE breaker that actually TRIPPED? Amazing.... [Linked Image]

Re: Vintage MotorHome #117935 07/20/04 12:50 AM
Joined: Apr 2004
Posts: 42
sparkystudent Offline
i see a red and a yellow wire to the ground buss and a yellow wire to the neutral buss. what is that to? doesnt look code compliant to me unless im wrong and it is ok for RV application or some such thing [Linked Image]. also was this an origonal equip. item or an after purchase addition?

Re: Vintage MotorHome #117936 07/20/04 01:06 AM
Joined: Jul 2003
Posts: 394
Big Jim Offline
I'm sure the red wire on the ground bus isn't compliant. I don't have a clue why but they used a piece of 12-3 for the water heater in place of the 12-2w/g for everything else. The two yellow wires feed a little neon on the outside beside the shore power cable box. The intent was a polarity warning. If you connected shore power and the light came on, you had a miswired source.
The unit was being fed from a 20 amp 120 circuit with an adapter. The FPE breaker tripped the first time I plugged in the juice. I reset it and it stayed reset. The GE protecting the outlet went first from then on. I believe the whole thing is OEM. I may have been the first one to ever take the cover off the box (after I removed the wood around it). I was also a little curious why there are a couple of circuits run thru separate KOs and all the rest are run thru a big nipple. From what I saw, whoever approved this system was pretty optimistic about romex and "dry" locations.

Re: Vintage MotorHome #117937 07/20/04 02:23 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline
British motorhome wiring is also frequently hidden away in inaccessible corners, making additions and tests very awkward sometimes.

A neon wired neutral-to-ground is also a common feature here to indicate reversed polarity on supplies, although without the complication of a 4-wire 120/240V hookup of course.

Re: Vintage MotorHome #117938 07/22/04 01:10 AM
Joined: Feb 2004
Posts: 1,436
Lostazhell Offline
A panel face up??? This can't be a good idea! I feel bad for anyone who might spill their "Super Big Gulp" while sitting over that thing! [Linked Image]

Re: Vintage MotorHome #117939 07/23/04 12:26 AM
Joined: Jul 2003
Posts: 394
Big Jim Offline
I'd be more worried about access in an emergency. It is under a 6" foam seat and under a 5/8" plywood (about 2 1/2 x 6 1/2 feet) bed extending piece then under the smaller wood cover you see in the picture.

Re: Vintage MotorHome #117940 07/23/04 05:42 PM
Joined: Nov 2002
Posts: 174
kale Offline
One time I had a used pickup camper that I had just purchased. When checking out the camper in my driveway, my son got a shock from the shell. I immediately disconnected the shore power and checked it out.

In the little load center, the neutral was bonded to the panel-like you would do on a service entrance. It appeared to have come from the factory that way.

The power inlet was wired backwards, the end result being the entire camper shell was hot and must have been that way from the day it left the factory floor.

Re: Vintage MotorHome #117941 07/29/04 05:07 AM
Joined: Jul 2003
Posts: 394
Big Jim Offline
When dealing with any kind of RV, there is but one safe assumption: assume it is totally screwed up and work from there. I am sure they see no form of outside inspection when they are built in a factory.
I volunteered in a summer camp one year. A staff member reported that she smelled gas in the RV she was living in. I went in and started looking. EVERY gas connection I could find was loose! This was a nice unit from a well known company. It really took me a couple of hours to settle my nerves after I finished defusing that bomb.


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